Here are a few pictures of one of our latest projects done at Weaver Motorsports this week. It's a 1998 BMW M Roadster and our customer has requested a full suspension upgrade. The car must be able to be used as a regular street car but with adjustable settings for track & autocross days. We suggested the Bilstein Sports for this setup as they have a slightly shorter length than the Bilstein HD's. The Sports are more suitable for this car, as the factory Roadster has slightly lower springs than the standard Z3.

While replacing the rear shocks we also replaced the rear shock mountings with the upgraded HP rubber/aluminium version from Turner Motorsports. We did away with the old noisy factory mountings and installed a mounting with a quieter and sturdier design. They look great too!

The rear sway bar was replaced with a 21mm H&R adjustable version to decrease body roll and to reduce the excessive under steer experienced with these models. Sport Sway Bars are designed for drivers who desire improved handling without lowering or affecting ride quality. H&R Sport Sway Bars increase your suspension’s roll stiffness or its resistance to roll in turns, while maintaining ride comfort and dramatically increasing cornering control, lateral stability, and grip.

We also replaced the original factory FCAB's (front control arm bushes) with upgraded stiffer urethane Powerflex variety from Bimmerworld. The front control arm bushings are one of the first parts to upgrade when looking to increase the handling performance of your E30/E36 3 Series or Z3. The stock bushings are extremely soft and wear quickly, causing unnecessary deflection, uneven tire wear, and bad steering feedback. These Powerflex front control arm bushings (FCAB) solve this issue by using 100% urethane construction. This bushing reduces control arm defection to a minimum, while still offering compliance for everyday use.

While installing the front struts we replaced the factory mountings with the KMAC stage 2 camber plates. The Stage 2 KMAC plates are a mixed street/track camber/caster plate meant to be used in a variety of suspensions. This design allows maximum range of adjustment since no other hardware interferes with the adjustments. These plates can work on both coil over and stock-type suspensions. The Stage 2 camber plates are shorter than a factory mount so may not be suitable for cars will little suspension travel. These are designed mainly for adding negative camber for improved handling. The beauty of these plates is that it literally takes 2 minutes to change them from regular road settings to maximum negative camber settings for track use. It's a matter of loosening 3 nuts, moving the plate in the desired direction and retightening. There is no need to lift up the wheels to make an adjustment.

All of the suspension components are available directly from us at the following prices:

I'm the owner of the M Roadster described above, and I'd just like to say that Simon and the team at Weaver Motorsports did a great job with this work. They helped me think through the parts selection process and some of the alternate ways the camber plates could be installed. The car is now MUCH better balanced on the track, with most of the tendency toward understeer gone or manageable through tire pressure adjustments. Additionally the Bilstein dampers are performing much better in the North Carolina heat than the factory units did.

Reply

Nic

2/20/2013 20:09:02

Bart. I have the same year/vehicle as you and plan to race is autocross CS class. I had not thought of camber plates. Did they help much? Also, did you modify brake components?

Reply

Bart C.

6/23/2015 09:35:55

Nic, sorry for the very late reply! Yes, the camber plates made a huge difference and I highly recommend them, although the K-MAC plates did not give me any additional caster beyond stock, so a camber-only plate might do just as well. On my car, with stock springs, the most aggressive settings available were -2.9 degrees camber and +7.9 degrees caster. I have not modified the brakes, other than going to Ate Blue fluid, since they have been more than adequate for autocrossing in stock form. I'd love to hear what you ended up doing with your car and how it worked out!

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